Process of manufacturing fuel briquettes

ABSTRACT

A process for manufacturing fuel briquettes from a mixture of (a) solid particles of a material which, if compressed alone in said process, would not briquette because of their relative inertness to the heat and pressure used in the process, and (b) particles of an operative binder material for the solid particles, the binder material consisting essentially of caking coal containing naturally occurring volatiles, including those which vaporize at temperatures in excess of 430*C., said process comprising: COMPRESSING AN ABOUT 73:27 PERCENT MIXTURE OF AT LEAST ONE MATERIAL (A) CHOSEN FROM THE GROUP CONSISTING OF ANTHRACITE, LOWVOLATILE COAL, LOW-TEMPERATURE CARBONIZATION COKE, COKE BREEZE, AND IRON ORE, AND AT LEAST ONE MATERIAL (B) CHOSEN FROM THE GROUP CONSISTING OF CAKING COAL, HIGH-VOLATILE COAL, GAS COAL, AND OPEN BURNING COAL, INTO BRIQUETTES AT A TEMPERATURE OF 430*-540*C tempering the hot briquettes thus formed, without raising the temperature thereof; THE MINIMUM DURATION OF THE TEMPERING IN MINUTES (T) AND THE MEAN TEMPERING TEMPERATURE IN *C (T) being determined in accordance with the relation

ilnited States Patent [1 1 Beckmann PROCESS OF MANUFACTURING FUEL BRIQUETTES [76] Inventor: Franz H. Beckmann, Stettiner Strasse 10, Alsdorf, Germany [22] Filed: Jan. 26, 1973 [21] Appl. No.: 326,978

Related U.S. Application Data [63] Continuation of Ser. No. 75,645, Sept. 25, 1970,

abandoned.

[52] US. Cl 44/10 H, 44/15 R, 75/42 [51] Int. Cl. C10l 5/00, C101 5/10, C101 5/40 [58] Field of Search 44/2, 10 R, 10 H; 10 J, 44/15 R, 23, 11-13; 75/3, 4, 42

[56] References Cited UNITED STATES PATENTS 2,466,435 4/l949 Jones et al. 44/23 X 3,027,306 3/1962 Miischenborn et al. 44/10 R 3,093,463 6/1963 Madley 44/10 R 3,l72,823 3/1965 John et al. 44/10 R 3,725,038 4/1973 Wenzel et al. 75/42 X Primary Examiner-C. F. Dees Attorney, Agent, or Firm-Cushman, Darby & Cushman Oct. 15, 1974 ABSTRACT A process for manufacturing fuel briquettes from a mixture of (a) solid particles of a material which, if compressed alone in said process, would not briquette because of their relative inertness to the heat and pressure used in the process, and (b) particles of an operative binder material for the solid particles, the binder material consisting essentially of-caking coal containing naturally occurring volatiles, including those which vaporize at temperatures in excess of 430C, said process comprising:

Compressing an about 73:27 percent mixture of at least one material (a) chosen from the group consisting of anthracite, low-volatile coal, low-temperature carbonization coke, coke breeze, and iron ore, and at least one material -(b) chosen from the group consisting of caking coal, high-volatile coal, gas coal, and open burning coal, into briquettes at a temperature of 430-540C tempering the hot briquettes thus formed, without raising the temperature thereof;

the minimum duration of the tempering in minutes (t) and the mean tempering temperature in (T) being determined in accordance with the relation 7 Claims, 3 Drawing Figures PROCESS OF MANUFACTURING FUEL BRIQUETTES This is a continuation, of application Ser. No. 75,645, tiled Sept. 25, 1970, now abandoned in favor hereof.

The invention relates to a process of manufacturing fuel briquettes by compressing a material composed mainly of non-softening solid substances and caking coal at a temperature of 430540C, and next cooling the briquettes formed. The invention also relates to apparatus for realizing this process.

For the manufacture of fuel briquettes several processes have been proposed. In the process of interest here, the mass to be briquetted, which contains disintegrated coal as a binder, is formed to briquettes on roller presses, ring-roll presses, or extruder presses. The greater part of the mass to be briquetted consists of inert material, i.e., material that is not deformed by heat; in the case of fuel briquettes this material is, for instance, low-volatile coal, low-temperature carbonization coke or coke breeze, and with ore briquettes it consists of iron ore, etc. During the compression stage, the mass to be briquetted is heated to about 450-540C, preferably to 450520C.

Immediately after the fuel briquettes have been formed they are slowly cooled on an air-cooling line, or

by means of a flushing gas with exclusion of air; too

rapid cooling detracts considerably from the strength of the briquettes. Fuel briquettes of 20-50 g slowly cooled immediately after their formation show a point load resistance of 70-160 kg, dependent on shape and size.

These point load resistances are still too low for highgrade products.

Another type of after-treatment known in the art is low-temperature carbonization or coking, in which process the fuel briquettes are subjected to a secondary degasification above the temperature used in pressing; this is applied for example in the manufacture of shaped coke. Generally, the product is not cooled between the briquetting stage and the secondary coking. A full secondary coking treatment raises the point load resistance to ISO-300 kg.

The object of the present invention is to effect a strengthening of fuel briquettes of the type meant above, without the pressing of the briquettes having to be followed with a low-temperature carbonization or coking treatment carried out at a temperature above the pressing temperature, and hence requiring additional heat supply.

it has now been found that the point load resistanc of fuel briquettes comprising two or more components can be considerably raised i.e., by more than kg if after their formation, the briquettes are subjected to a tempering treatment at or below the pressing temperature, the minimum duration of the tempering in minutes (t) and the mean tempering temperature in C (T) being determined in accordance with the relation By tempering is here to be understood keeping the formed product at about the same temperature for some time;

Evidently, the strengthening effected by the shaping and compression of the briquetting material is not completed yet immediately after the pressing treatment. In

thetemperature range between 400 and 540C processes take place in the briquetted material which, in

dependence on the tempering time, result in a considerable strengthening of the fuel briquettes close under the pressing temperature.

Preferably, the minimum duration of the tempering is 30 minutes.

Unlike secondary low-temperature carbonization 0r coking,which effects a considerable decrease of the volatile content, the tempering according to the invention of briquettes mainly composed of non-softening solid substances within the abovementioned temperature range results in only a slight change of the volatile content of the fuel briquettes, in general not more than 2 percent. Thanks to the fact that the tempering of briquettes according to the invention can take place in the temperature range immediately under the pressing temperature it is not necessary to supply extra heat to carry into effect the process according to the invention.

sulting in an increase of the mean point load resistance by more than one third of the original value was found empirically. It should be remarked here that the formula given above represents only the numerical correlation of the minimum tempering time and the mean tempering temperature and has no further mathematical meaning.

The invention will be further elucidated with reference to the drawing, in which FIG. 1 is a diagram showing the interrelation of time, temperature and point load resistance,

FIG. 2 is a block diagram showing the increase of the point load resistance;

FIG. 3 is a diagrammatical representation of a briquetting plant.

FIG. 1 shows the point load resistancesof product briquettes measured after exposures of up to minutes to temperatures between 400 and 540C. The curves of equal point load resistance relate to 20- gr amme' fuel briquettes and were established in model tests on a laboratory scale. The abscissa shows the tempering time, the ordinate the temperature at which the tempering took place. The point load resistances of the fuel briquettes, measured after slow cooling immediately following the briquetting, was 80 kg. The curves show, for instance, that the average strength of fuel briquettes is raised to kg by 40 minutes tempering at 500C.

FIG. 2 shows the distribution of the point load resistance" of industrially manufactured fuel briquettes and the change in resistance effected by applying the tempering according to the invention under process conditions. The fuel briquettes, which had a weight of 20 g, had been made from 73 percent of anthracite and lowvolatile coal and 27 percent of high-volatile coal (with an average volatile content of 22 percent), in accor- Over the letters A, B, C, D and E, FIG. 2 shows the mean point load resistances of 20 percent portions of the average samples examined. A denotes the portions of lowest point load resistance, B the portions of nexthigher point-load resistance, etc. The point load resistanc'es (open bars) were first measured on untempered fuel briquettes, which had been slowly cooled immediately after their formation. The point load resistances of the briquettes tempered according to the invention (solid bars) were measured after tempering at the temperatures and for the times noted, followed by rapid cooling by a water spray.

FIG. 2 shows that, statistically, the percentage increase of the point load resistance is greater according as the comparative product was harder.

It should be noted that if in the industrial application of the process the duration of the tempering treatment is over 30 minutes, the increase of the point load resistance shows a stronger dependence on time than it does in the model tests on a laboratory scale. In practive, therefore, it is preferable to use tempering times of over 30 minutes.

The use of an oxygenous atmosphere within the temperature range according to the invention immediately gives rise to combustion reactions, and hence to an undesirable temperature rise. For this reason, the oxygen content of the atmosphere enveloping the fuel briquettes during their tempering should in normal cases be kept below 3 percent. v

The new recognition with regard to the strengthening that takes place in fuel briquette tempered at 400-540C immediately after their formation can be advantageously utilized in practice in a simple way. The apparatus used for the realization of the process is characterized in that the briquetting press, is followed by at least one container of such capacity that the residence time of the individual briquettes in it is more than 30 minutes.

In carrying out the process according to the invention, the briquettes are introduced into a bunker with suitable gas-tight closing means. If this container is in-. stalled in the immediate vicinity of the press, the temperature of the briquettes does not fall off by more than l20C, even if no use is made of a costly insulation. If the temperature of the mass to be briquetted is, e.g., 470-500C before the press which temperature range is normally applied in the manufacture of fuel briquettes from non-caking low-volatile coal with a binder consisting of high-volatile coal ,the temperature of the material during and immediately after the briquetting treatment will be 480-520C. The temperature rise is caused by the compression energy applied. In this case the temperature of the briquettes in the hot bunker will be about 470490C. Storage of the hot briquettes at this temperature for over 30 minutes effccts the desirable strengthening without this requiring passes through a heating tube 2. The anthracite (A) is added somewhere near the middle of the tube line 2. Both components are separated from the gas in a cyclone 3. Thereafter, the high-volatile coal (F) is fed into a heating tube 4, through which flows the fuel gas, which has meanwhile cooled down to 700-800C. The high-volatile coal issuing from cyclone 5 is intimately mixedwith the coals of lower volatility in a mixer 6, and the mixture is supplied to a roller press 7. If use is made of the coals mentioned above the temperature in the mixer 6 is 490C.

Immediately after leaving the press 7, the fuel briquettes have a temperature of 500 to 505C. At this temperature they are fed into hot bunker 9 and 10 through a rotary discharger 8. The bunkers are filled successively with fuel briquettes and also discharged the one after the other. Each bunker has such a size that the tempering time of the briquettes can be chosen between 30 min. and 6 hours. The bottom of each bunker is provided with an outlet. 1 1 with virtually gas-tight closing means. The tempered product is carried off on a conveyor belt and subjected to an immersion treatment at 13, tobe cooled to about l30CQImmediately before the briquettes are loaded for transport, they are finally cooled by means of one or more sprays 14.

It should be pointed out that the use of the process accordingto the invention is not restricted to the above mode of realization. For instance, it is also possible to use for the tempering treatment a container through which the briquettes travel in a continuous stream, e.g., under gravity, or through which they are conveyed along a horizontal path, at such a rate that the residence time of the individual briquettes is within the duration of the temperingmentioned above.

What is claimed is: V

l. A process for manufacturing fuel briquettes from a mixture of a solid particles of a material which, if compressed alone in said processfiivofild not bri quette because of their relative inertness to the heat and pressure used in the process, and (b) particles of an opera- I tive binder material for the solid particles, the binder the supply of additional heat.

material consisting essentially of caking coal containing naturally occurring volatiles, including those which vaporize at temperatures in excess of 430C, said process comprising:

compressing an about 73:27 percent mixture of at least onematerial (a) chosen from the group consisting of anthracite, low-volatile coal, lowtemperature carbonization coke, coke breeze, and t iron ore', and at least one material (b) chosen from the group consisting of caking coal, high-volatile coal, gas coal, and open burning coal, into briquettes at a temperature of 430540C. tempering the hotbriquettes thus formed, without raising the temperature thereof; the minimum :duration'of' the tempering in minutes (t) and the mean tempering temperature in C (T) being determined in accordance with the relation .of the atmosphere within the bunker is maintained 2. The process of claim 1 wherein the minimum'duration of the tempering step is at least 30 minutes.

3. The process of .claim 1 wherein the tempering is accomplished by enclosing the hot briquettes in a bun- I ker from which the briquettes are removed after 30 minutes to 6 hours at a temperature of about 4. The process of claim 3 wherein the oxygen content 6. The process of claim 5 wherein the briquettes are cooled by spraying them with water.

7.- The process of claim 5 wherein the briquettes are cooled by immersing them in water. i 

1. A PROCESS FOR MANUFACTURING FUEL BRIQUETTES FROM A MIXTURE OF (A) SOLID PARTICLES OF A MATERIAL WHICH, IF COMPRESSED ALONE IN SAID PROCESS, WOULD NOT BRIQUETTE BECAUSE OF THEIR RELATIVE INERTNESS TO THE HEAT AND PRESSURE USED IN THE PROCESS, AND (B) PARTICLES OF AN OPERATIVE BINDER MATERIAL FOR THE SOLID PARTICLES, THE BINDER MATERIAL CONSISTING ESSENTIALLY OF CAKING COAL CONTAINING NATURALLY OCCURRING VOLATILES, INCLUDING THOSE WHICH VAPORIZE AT TEMPERATURES IN EXCESS OF 430*C., SAID PROCESS COMPRISING: COMPRESSING AN ABOUT 73:27 PERCENT MIXTURE OF AT LEAST ONE MATERIAL (A) CHOSEN FROM THE GROUP CONSISTING OF ANTHRACITE, LOW-VOLATILE COAL, LOW-TEMPERATURE CARBONIZATION COKE, COKE BREEZE, AND IRON ORE, AND AT LEAST ONE MATERIAL (B) CHOSEN FROM THE GROUP CONSISTING OF CAKE COAL, HIGH-VOLATILE COAL, GAS COAL, AND OPEN BURNING COAL, INTO BRIQUETTES AT A TEMPERATURE OF 430*-540*C. TEMPERTING THE HOT BRIQUETTES THUS FORMED, WITHOUT RAISING THE TEMPERATURE THEREOF; THE MINIMUM DURATION OF THE TEMPERING IN MINUTES (T) AND THE MEANS TEMPERING TEMPERATURE IN *C (T) BEING DETERMINED IN ACCORDANCE WITH THE RELATION T = 2,000/(T - 390).
 2. The process of claim 1 wherein the minimum duration of the tempering step is at least 30 minutes.
 3. The process of claim 1 wherein the tempering is accomplished by enclosing the hot briquettes in a bunker from which the briquettes are removed after 30 minutes to 6 hours at a temperature of about 470*-490*C.
 4. The process of claim 3 wherein the oxygen content of the atmosphere within the bunker is maintained below 3 percenT by volume during tempering.
 5. The process of claim 1 including the subsequent step of rapidly cooling the tempered briquettes to at least as low as 130*C.
 6. The process of claim 5 wherein the briquettes are cooled by spraying them with water.
 7. The process of claim 5 wherein the briquettes are cooled by immersing them in water. 